The invention relates generally to a downrigger line clamp mechanism used in downrigger fishing.
When trolling for fish, a downrigger assembly can be used to control the depth at which the lure is trolled through the water. A downrigger typically comprises a weight suspended from the boat by a downrigger cable; and a leader line, one end of which is clipped to the downrigger cable and the other end of which is clipped to the fishing line, typically 10 to 30 feet from the lure, with a line clamp. When trolling with a downrigger, the fishing line runs substantially vertically from the fishing rod to the line clamp and substantially horizontally (depending on the trolling speed, and the drag of the lure and line) from the release clamp to the lure.
When a fish is hooked, it is necessary for the line clamp to release the fishing line so that fish can be played free of the hindrance of the weight, and brought aboard without tangling the fishing line and the cable. To operate properly, the line clamp must retain the fishing line during trolling and release the fishing line when a fish strikes the lure. Typically, persons fishing desire different line clamp release tensions depending on the fishing technique and the type of fish being sought. It is therefore advantageous to be able to adjust the line clamp release tension.
Most downrigger line clamps use a coil compression spring to bias two pivoting clamping surfaces towards a closed position wherein a fishing line may be frictionally held between the clamping surfaces. Such systems are described in U.S. Pat. No. 5,784,826 (Walker, Jul. 28, 1998), U.S. Pat. No. 5,950,349 (Walker, Sep. 14, 1999), U.S. Pat. No. 5,979,104 (Walker, Nov. 9, 1999), U.S. Pat. No. 4,698,933 (Shaw, Oct. 13, 1987), and U.S. Pat. No. 5,163,246 (Shaw, Nov. 17, 1992).
With the foregoing line clamps, the friction holding the fishing line between the clamping surfaces will vary depending upon the character and condition of the line as well as the specifics of the surface-to-surface contact of the clamping surfaces with the line that happen to occur in a given clamping event. In other words, for a given clamping compressive force, the force of friction will vary from one clamping event to the next, and consequently the line release force will also vary somewhat.
The pivot-based line clamps of the foregoing sort enable the person using them to vary the release tension by changing the position of the fishing line between the clamping surfaces. Specifically, a fishing line is more readily released from between the clamping surfaces if the fishing line is positioned near the ends of the clamping surfaces than if the fishing line is positioned closer to the pivot. The leverage is greater and the release tension is higher near the pivot point than they are further away from the pivot point.
It is therefore possible to make minor adjustments to the line clamp release tension by carefully positioning the fishing line between the clamping surfaces. In practice, however, such previously known pivot-type clamps are effective to provide only a fairly limited range of release tensions. Accordingly, several of these aforementioned patented systems describe additional structure and/or techniques for enabling various release tensions of the fishing line, namely by providing auxiliary means for adjusting the compression force between the clamping surfaces. In particular, U.S. Pat. Nos. 5,784,826, 5,950,349, and 5,979,104 describe a cam lever adjustment assembly wherein a threaded rod is inserted through a bore through the clamping surfaces. The ends of the threaded rod protrude from the outer clamping surfaces and may be threadedly engaged by any one of a number of different types of internally threaded rod caps each of which may be tightened or loosened to vary the compression adjustment between the clamping plates. Typically, the rod caps have wings, knurled surfaces or other projections, to make it easier to turn them by hand.
One disadvantage of the aforementioned prior designs is that the compression force adjustment devices are somewhat finicky to operate, which can be a hindrance for a fisherman whose hands are already occupied with fishing line, lures, flashers, and bait, and whose hands may be somewhat greasy as a consequence.
Furthermore, the aforementioned designs do not permit a smooth flow of water over the surfaces of the line clamp. In the aforementioned designs, coil springs, thumb or wing nuts, and levers protrude beyond the body of the fishing line clamp, thereby causing turbulence around the line clamp as it passes through the water. An unbalanced line clamp or a line clamp that is not streamlined may twist the fishing line and reduce the performance of the lure. Furthermore, a fishing line may hang up the protrusions of the line clamp, thereby leading to tangled lines.
Another type of prior line clamp is described in U.S. Pat. No. 5,921,015 (Newell et al., Jul. 13, 1999). As with the aforementioned line clamp designs, this patent describes a line clamp having two pivoted clamping plates between which a fishing line may be frictionally held. Unlike the aforementioned designs, however, rather than using a coil compression spring to clamp together the plates, the elongated clamping plates are sandwiched together by a rigid sliding clamp that slides along the outer surfaces of the elongated clamping plates from the pivot towards the ends of the plates and locks in place when the clamp is in the correct position to provide a desired clamping force.
As with the previously mentioned coil-spring-based line clamp, the line clamp described in U.S. Pat. No. 5,921,015 is fairly complex and expensive to manufacture; the overall shape of the line clamp is not streamlined and the sliding clamps are difficult to operate.
What is required is a simple, streamlined line clamp with a simple, easy-to-operate compression force adjustment device that enables a suitable range of release tensions of the fishing line.
An object of the invention is to provide a line clamp mechanism having means for adjusting the line clamp compression force that is simple, streamlined and relatively inexpensive to manufacture. As in other previously known downrigger clamp designs, the fishing line is releasably frictionally held within the downrigger line clamp, permitting the fishing line to be pulled from the downrigger line clamp by a fish striking the lure. According to one aspect of the invention, there is provided a pre-stressed line clamp mechanism having the following components:
(a) first and second elongate arms each made of suitable selected elastic material and each having a clamping jaw at its distal end, a compression-adjusting end at its proximal end, and an outwardly bulging arcuate grip portion intermediate the clamping jaw and the compression-adjusting end;
the second elongate arm being longitudinally generally coextensive with the first elongate arm, and oriented in opposition to the first elongate arm so that, the clamping jaws of the two arms present opposed clamping faces, preferably generally planar and generally parallel to one another, suitable for clamping a line therebetween, and the compression-adjusting ends of the two arms present opposed abutting surfaces;
(b) a coupling means such as a pivot pin or equivalent on which both the arms are pivotally mounted, to provide pivoting of the distal portions of the arms through a small angular range about a pivotal axis located near the distal ends of the arms, the clamping jaws extending distally away from the pivot pin and the grip portions extending proximally away from the pivot pin;
the outwardly-bulging grip portions of the opposed arms forming a grip that under compressive force exerted by the user""s hand forces disengagement of the clamping faces to permit insertion or release of a fish line, and in rest position are stressed so as to exert a compressive force against one another at the abutting surfaces, thereby biassing the clamping jaws together toward a closed clamping position in which clamping force may be applied to a fish line inserted and held between the clamping faces; the amount of clamping force being variable with distance from the pivot pin; the material, shape and dimensions of the arms being selected so that within engineering tolerances, the compressive force exerted by the clamping jaws on the fish line, and consequently the release tension of the fish line, are within predetermined selected ranges;
(c) leader line attachment means connected to the proximal end of at least one of the arms and preferably both arms; and
(d) an adjustable compression-force biassing device movably mounted between the compression-adjusting ends of the arms, the biassing device having one or more spacers, or one or more spacers and an abutment opening within which the opposed abutting surfaces of the compression-adjusting ends can abut, so as to selectably provide at least two different spacing dimensions between the abutting surfaces of the compression-adjusting ends; one bearing surface of each said spacer making sliding contact with an abutting surface of the compression-adjusting end of an associated one of the arms, and the other bearing surface of each said spacer making sliding contact with an abutting surface of the compression-adjusting end of the other of the arms; each spacer or abutment opening being positionable into an active position relative to the abutting surfaces of the compression-adjusting ends by moving the biassing device distally or proximally relative to the arms;
wherein the magnitude of the compression force exerted by the jaws is adjustable by adjusting the distal/proximal position of the biassing device relative to the arms.
In a preferred embodiment, the adjustable compression-force biassing device is mounted for distal/proximal displacement relative to the arms, the spacers, or the spacers and the abutment opening, being disposed in longitudinal series, each spacer or the abutment opening occupying a short portion of the longitudinal length of the biassing device and in turn brought into active position as the biassing device is proximally or distally displaced. Further, to prevent unwanted proximal or distal displacement that could, if permitted, present an unwanted spacer or the abutment opening in the active position relative to the abutting surfaces of the compression-adjusting ends, the biassing device is provided with active position stabilizers, such as ridges that engage mating slots, steps, rails, abutments or the like, that impede longitudinal displacement of the biassing device once a selected spacer is in the active position. The user may, by exerting a proximally or distally directed force on the biassing device, move the biassing device so that the spacer, or the abutment opening, that was in active position is displaced out of active position and replaced by the next spacer in the series.
For most purposes, a biassing device that includes two different spacers in longitudinal series, or an abutment opening and a spacer in longitudinal series; and therefore provides two available different line clamping forces at any given position of the line between the clamping jaws, suffices.
Also in the preferred embodiment, sleeves or sheaths are provided for the clamping jaws that envelope the clamping jaws. These sleeves or sheaths may advantageously be provided with relatively high-friction clamping surfaces overlying the clamping faces of the clamping jaws. A securing device such as a slot in the sleeve or sheath that engages a projection on the outward-facing side of the associated clamping jaw impedes unwanted removal of the sleeve or sheath from the clamping jaw. Reference in this specification to the clamping jaws or the clamping faces should be understood to include the possibility that the composite clamping jaws may include such sleeves or sheaths and that the clamping surfaces are formed by opposed relatively flat portions of the sleeves or sheaths. The sleeves or sheaths provide enhanced gripping and increased cushioning of the fishing line.
The shape, dimensions and material of the arms are selected to enable the arms to resiliently flex when the line clamp mechanism is being assembled, thereby to pre-stress the clamping mechanism. What has been referred to in the interest of simplification as a xe2x80x9cpivot pinxe2x80x9d is preferably a pair of gudgeons, a respective one of which is moulded on each arm proximally to the clamping jaw, and a pin insertable through the gudgeons to provide the pivoting connection. The stress occurs because when the arms are not attached to each other and are disposed in relaxed opposed relationship with their compression-adjusting ends in contact and their clamping surfaces in contact, the bow-like shaping of the arms from one end to another results in a misalignment of the gudgeon holes in the first arm with the gudgeon holes in the second arm, in that the portion of each arm proximate to the gudgeons is outward of the position where the gudgeon holes would align. The arms must be forced inwardly toward one another to enable them to be coupled together by the pivot pin. The result, when the arms are thus coupled together, is a compressive force exerted by the clamping jaws. This compressive force may be released by pressing the gripping portions of the arms inwardly toward one another. The rest compressive clamping force may be adjusted by adjusting the spacing between the compression-adjusting ends of the arms, and this spacing adjustment is accomplished in the preferred embodiment by varying the longitudinal position of the biassing device, thereby to provide as many different spacings between the compression-adjusting ends of the arms as there are spacers. Further note that, as mentioned above, in one position of the biassing device, there need not be a spacer interposed between the compression-adjusting ends; these ends may abut one another within the abutment opening.
Preferably, each arm is smoothly convexly outwardly curved to distribute the stress throughout the arm, and to provide an aesthetically pleasing design that is both streamlined (for facilitating minimization of turbulence as the line clamp passes through the water), and ergonomic (for ease of gripping and squeezing). The arms desirably have maximum curvature towards their proximal ends and may suitably straighten in the vicinity of the pivot pin. Other shapes may better facilitate minimization of turbulence. Other shapes may be selected at the preference of the designer if they at least provide a suitable gripping means and downrigger attachment means, provide the requisite resilient flexing when the line clamp mechanism is being assembled, and provide pre-stressing of the arms when assembled so that a compressive force exists between the clamping jaws, releasable upon compression of the gripping means. The arms are preferably moulded from a hard durable plastic material such as a suitable acetal resin or composite, but may also be suitably formed by other known means, and made from other similarly resiliently flexible and durable materials. The transverse dimension of each arm may be varied from distal to proximal end to provide adequate surface contact of the line within the clamping jaws while avoiding a cumbersome grip. The thickness of the arms may be varied, preferably ranging from a maximum in the vicinity of the clamping jaws and a minimum near the compression-adjusting ends of the arms, for ease of squeezing. The inner portions of the arms on the proximal side of and nearer the pivot pin may be provided with proximally/distally extending stiffeners for greater resistance to flexing in those portions of the arms.
In this specification, including the claims, the following words have the following meanings:
(a) The words xe2x80x9cdistalxe2x80x9d and xe2x80x9cproximalxe2x80x9d refer to the respective ends and proximate parts of the line clamp relative to the position of the downrigger cable when the line clamp is in use. The distal end of the line clamp is the end of the line clamp that is furthest from the downrigger cable during normal trolling, and the proximal end of the line clamp is the end of the line clamp that is closest to the downrigger cable during normal trolling. xe2x80x9cProximal/distalxe2x80x9d and xe2x80x9cdistal/proximalxe2x80x9d both refer to directions that are substantially toward the proximal end or the distal end of the line clamp, as the case may be.
(b) The words xe2x80x9cinwardxe2x80x9d and xe2x80x9coutwardxe2x80x9d are used relative to an imaginary plane roughly defined by the opposed contacting jaw surfaces of the clamp, the imaginary plane being perpendicular to the compressive clamping force. An inward direction is one towards the imaginary plane from either side of the imaginary plane. An outward direction is one away from either side of the imaginary plane.
(c) The transverse dimension is the dimension lying within the imaginary plane and perpendicular to the longitudinal dimension.
The leader line attachment means is suitably a hole through the compression-adjusting end of each arm. The biassing device is preferably moulded, with its spacer or spacers, as a single integral unit, and is configured so that it may be easily inserted and secured between the compression-adjusting ends of the arms, providing at its proximal end a relatively large opening that affords ample clearance for insertion of the leader line into the leader attachment means in the compression-adjusting ends of the arms. The terminating portions of the compression-adjusting ends of the arms may be slightly outwardly bent for ease of insertion of the biassing device therebetween.
In the operation of the line clamp mechanism according to this aspect of the invention, the jaws are opened to receive a fishing line by squeezing together the squeezable grip portions of the arms. The release tension required to release the fishing line from between the jaws of the line clamp is in part dependent upon the positioning of the fishing line within the jaws; the compression force of the jaws is less towards the distal ends of the jaws and increases in the proximal direction toward the pivot pin. Furthermore, the biassing device may be used to adjust the compression force between the jaws by moving one of the spacers thereof into an active position between the compression-adjusting ends of each arm; the greater the spacing dimension between the compression-adjusting ends of the arms, the higher the compression force between the jaws.
With line clamps where the release tension is low, the compressive force between the compression-adjusting ends is also relatively low and the compression-adjusting ends do not grip the biassing device as tightly as they do when the compressive force is relatively high. In a preferred embodiment, for use in line clamps where a low release tension is desired, the compression-adjusting end of one arm has an inwardly projecting peg and the compression-adjusting end of the other arm has a hole sized, shaped and positioned to slidably mateably engage the peg. The peg has a leader line hole through which a leader line can be inserted. The peg is contained within a slot in the biassing device and thereby acts to prevent the biassing device from being dislodged from between the compression-adjusting ends.
The invention as described above offers several features over the prior line clamp mechanisms. Firstly, since the compression force between the jaws is provided by the resilience of the plastic arms, the line clamp according to the preferred embodiment of the invention is suitably more streamlined than conventional line clamps which are required to incorporate coil springs, compression clamps and thumb, or wing, nuts into the design. Secondly, as opposed to the fishing line clamp pads as used in prior line clamps, the soft grip jacket functions both to cushion the fishing line as well as shield the fishing line from the pivot, thereby helping to reduce fishing line hangups. Thirdly, the line clamp mechanism includes a simple biassing device to adjust the compression force between the jaw surfaces of the line clamp mechanism thereby adjusting the amount of tension which is required to release the fishing line from between the jaws. Lastly, with the exception of the jacket, the entire line clamp mechanism is made from an acetal composite. All components of the line clamp mechanism may be made of materials selected to be essentially impervious to harm from immersion in fresh or salt water. The line clamp is relatively inexpensive to manufacture and easy to assemble, and may, if suitably designed in accordance with the teachings herein, be operated with one hand.
The various features of novelty that characterize the invention are pointed out with more particularity in the claims annexed to and forming part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.